The Slovenly Saint and the Health-Conscious Devil

Aria, an honor student and prefect at her magic school, has just one problem—Jade, the black mage. He is known for being cold and harsh toward his peers, and Aria has been doing her best to avoid him. But when she runs into him by accident, she hears...his thoughts?! Now that she knows what he's thinking, he's almost kind of cute... 

(Source: Yen Press)